1. Field of the Invention
The present invention relates to a mandibular motion diagnostic device for measuring the mandibular motion and reproducing it precisely as motion of a model of the mandible.
2. Prior Art
Analysis of the mandibular motion is an important factor which constitutes the basis for reconstruction of occlusion, diagnosis of gnatho-oral cavity system etc., but hitherto there has been developed no device for precise measurement of the mandibular motion and for reproducing it for close analysis.
Hence, in the occlusal diagnosis, manufacture of crown bridges or prostheses in the dental practice, one has had to resort to adjustments on trial-and-error basis or by methods not only troublesome but also requiring skill. In the manufacture of prostheses, in particular, imperfect adjustment is known to possibly cause gnatho-articular diseases, to say nothing of interfering with satisfactory masticatory function of teeth. The adaptability of prostheses made by such conventional methods to the patient cannot be seen unless they are tested by actually fitting in the mouth of the patient; and the major cause for the inevitable dependence on trial-and-error adjustments has been the absence of effective means for tracing the cause or causes of irregular loads on the condyle head which is known to be most closely associated with gnatho-articular disorders. Hence, it has been and is desireable to have an effective and reliable means, which enable quantitative reproduction of the mandibular motion of individual patients and allow arbitrary setting of the position of condyle head for accurately grasping the motion of condyle head so as to enable proper, reliable diagnosis of irregular motions.
From this point of view, there have been made attempts to measure the mandibular motion by fixing a tiny magnet or spotlight source at the tip of the mandible and detecting the motion of the magnet or light source (e.g. Japanese Patent Publication Sho-52-317, Japanese Patent Publication Sho-57-4253).
All these prior arts, however, grasp the mandibular motion of a single point, and do not measure the motion of the mandible as a whole which is complicated three-dimensional motion. If measurement could be done with a high precision, the motion of the mandible cannot be grasped accurately and analysis made on the basis of such measured data is nothing more than an approximate one. When analysis and diagnosis are made of the mandibular motion reproduced on the basis of such information, accurate and necessary information is difficult to read from general observation of the mandibular motion since it is a three-dimensional motion viewed on a monitor, which is two-dimensional. Since all such efforts amounted to nothing more than a mere simulation, there is a high hurdle to be cleared before proceeding to the next step of reconstruction of the occlusion. Also, despite the fact that proper occlusion, especially in the vicinity of where cusps are engaged, is essential for proper motion of the jaws as a whole, accurate measurement thereof could not be hoped for.